1. Field of the Invention
The present invention relates generally to a method and apparatus for changing a display mode. More particularly, the present invention relates to a method and apparatus for changing a display mode for a graphical user interface.
2. Description of the Related Art
Graphical user interfaces are used in many different applications, including laptops, personal computers, kiosks, personal digital assistants, cell phones, and televisions. A graphical user interface is any device capable of emitting light that is viewable by a user.
Graphical user interface technology has evolved due to a number of factors, including spatial limitations, power consumption, weight, image quality, response time, color gamut, and viewing angle. In this regard, older cathode ray tube graphical user interface technology has given way to liquid crystal display and plasma display panel technologies.
Because the display of some current graphical user interfaces may be viewed from wide viewing angles, the privacy of the user utilizing the graphical user interface may be compromised. A viewing angle is the maximum angle at which a graphical user interface may be displayed without an unacceptable degradation in image quality. For example, when viewed at angles greater than the viewing angle, the image displayed by a graphical user interface may appear poorly saturated, darkened, garbled, faint, blurry, or have poor contrast.
The viewing angle may be measured from one side of the graphical user interface to the opposite. The bisector of the viewing angle may be a line that is perpendicular to the plane defined by the flat surface of the graphical user interface. The viewing angle may also be measured along a horizontal, vertical, or any other axis relative to the graphical user interface.
In determining a viewing angle, the criteria by which an unacceptable degradation in image quality, if measured, may vary. For example, the viewing angle may be determined to be the thresholds at which the luminance of a graphical user interface is one-half of the graphical user interface's maximum luminance. The contrast ratio may also be used to determine the viewing angle. For example, the viewing angle may be determined to be the thresholds at which the contrast ratio of a graphical user interface exceeds 5:1 or 10:1.
Wide viewing angles may compromise the privacy of a user utilizing a graphical user interface by allowing persons other than the user to view the graphical user interface. For example, strangers may be able to see the personal data related to a user who is using a laptop in a public setting. In another example, secure information may be compromised if unauthorized persons are allowed to view, from a large viewing angle, data emitted from a graphical user interface.
One current device for increasing the privacy of a user utilizing a graphical user interface having a wide viewing angle is a screen that is placed in front on the graphical user interface. For example, this screen may be placed in front of a laptop monitor. However, although such screen are designed to block viewing outside of a predetermined viewing angle, such screen also cause an unacceptable degradation in image quality inside of the viewing angle as well. For example, the brightness of the image inside of the viewing angle may be severely compromised.
Also, the currently used screens must be inconveniently transported and kept near the graphical user interface. These screens may also become blurry or scratched over time. Hence, frequent replacement of such screens may be necessary.